The present invention relates to the general field of aviation turbine engines.
The invention relates more particularly to a system for de-icing an inlet cone of an aviation turbine engine having a ducted fan.
During certain stages of flight, and in particular at high altitudes where temperatures are low, blocks of ice of large size frequently form on certain portions of the engine, and in particular on the inlet cone.
FIG. 1 is a simplified section view of an aviation turbine engine having a ducted fan centered on a longitudinal axis X-X, and it shows the risks associated with a block of ice 2 forming on an inlet cone 1. In this figure, it can be seen that pieces of ice becoming detached from the block of ice 2 can give rise to impacts against pieces of equipment further downstream such as a fan blade 3, an outlet guide vane (OGV) 4 in the bypass passage 5, blades of a compressor 6 in the primary passage 7, and acoustic panels situated on the fairing of the fan 8, and can even be ingested in the primary passage 7, reaching the combustion chamber 9 with the resulting risk of extinguishing combustion.
Parts that are nowadays made for the most part out of composite material for reasons of performance of weight, such as the fan blades, the guide vanes, or the compressor blades are also more sensitive to such impacts than are parts made of metal.
The consequences of a block of ice that has formed on the inlet cone becoming detached can thus be expensive in terms of maintenance and replacing damaged parts, and can also degrade the performance and the reliability of the turbine engine, which might flame out if a block of large size is ingested.
It is therefore desirable to have a de-icing system that serves to prevent blocks of ice forming on the inlet cone, or at very least to reduce their size.
Document EP 1 840 028 discloses a system for de-icing a turbine engine inlet cone for aircraft in which hot air taken from a bearing enclosure of the engine is taken towards the inlet cone in order to heat it. The device described in that document makes provision in particular for discharging the hot air delivered to the inlet cone into the primary and bypass passages of the engine via openings situated in the inlet cone.
Nevertheless, such a solution can present certain drawbacks. In particular when the fan blades are made of composite material, the hot air coming from the de-icing system (which operates as soon as the turbine engine has started) heats the roots of the blades and creates a temperature gradient between the roots and the tips of the blades, which can degrade their mechanical strength.
Furthermore, the hot air coming from the de-icing system can be ingested by the primary passage, which can degrade the overall performance of the engine.
Finally, droplets of oil coming from the lubrication bearing enclosure might be present in this discharged hot air. If such droplets are then ingested in the primary passage of the engine, they can give rise to risks of corrosion and/or oxidation of metal parts present in the primary passage and to degraded overall performance of the engine.